50 Prior, therefore, to entering upon this most difficult path, all who by experience know they are too weak in spirit should humbly heed this warning of Paul the Apostle: "But if they do not contain themselves, let them marry. For it is better to marry than to be burnt." For many, undoubtedly, the burden of perpetual continence is a heavier one than they should be persuaded to shoulder. And so priests, who are under grave obligation of helping by their advice young people who declare they are drawn by some movement of soul to aspire to the priesthood or enter religious life, must urge them to ponder the matter carefully, lest they enter a way which they cannot hope to follow sturdily and happily to its end. They should prudently examine the fitness of candidates, even obtaining, as often as is proper, the opinion of experts; and then, if serious doubt remains, especially if it is based on past experience, they should make use of their authority to make candidates cease from seeking a state of perfect chastity, nor should these latter ever be admitted to Holy Orders, or to religious profession.
Source: Sacra Virginitas (Vatican.va)